Conversely, I find his comment to be perfectly matter-of-fact, whereas I find yours (esp. your last paragraph) comes across as condescending, haughty and (ironically) arrogant.
I wasn't kidding when I said it reminded me of the attitude some of the nastiest people adopt when dealing with CSRs. Completely forgetting the human element and just demanding things all the time. A HN comment has even less of a say in whether a site be taken down.
Humility isn't a sin. How hard can it be to stop at "This site is insecure."?
If it's potentially exposing the personal information of others, yes. The fact that the above statement values the hypothetical feelings of a person providing the aforementioned site rather than the personal information potentially exposed by anyone using the site suggests that perhaps priorities have not been evaluated properly.
My statement was simple, short, and to the point. No criticism of its author was made nor intended.
There is no excuse these days for not protecting your users' data. It should be taken down and secured ASAP.